Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C221/00—Preparation of compounds containing amino groups and doubly-bound oxygen atoms bound to the same carbon skeleton
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C201/00—Preparation of esters of nitric or nitrous acid or of compounds containing nitro or nitroso groups bound to a carbon skeleton
  • C07C201/06—Preparation of nitro compounds
  • C07C201/08—Preparation of nitro compounds by substitution of hydrogen atoms by nitro groups
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C201/00—Preparation of esters of nitric or nitrous acid or of compounds containing nitro or nitroso groups bound to a carbon skeleton
  • C07C201/06—Preparation of nitro compounds
  • C07C201/12—Preparation of nitro compounds by reactions not involving the formation of nitro groups
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C205/00—Compounds containing nitro groups bound to a carbon skeleton
  • C07C205/45—Compounds containing nitro groups bound to a carbon skeleton the carbon skeleton being further substituted by at least one doubly—bound oxygen atom, not being part of a —CHO group
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
  • C07C29/36—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring increasing the number of carbon atoms by reactions with formation of hydroxy groups, which may occur via intermediates being derivatives of hydroxy, e.g. O-metal
  • C07C29/38—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring increasing the number of carbon atoms by reactions with formation of hydroxy groups, which may occur via intermediates being derivatives of hydroxy, e.g. O-metal by reaction with aldehydes or ketones
  • C07C29/40—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring increasing the number of carbon atoms by reactions with formation of hydroxy groups, which may occur via intermediates being derivatives of hydroxy, e.g. O-metal by reaction with aldehydes or ketones with compounds containing carbon-to-metal bonds
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
  • C07C45/27—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation
  • C07C45/30—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with halogen containing compounds, e.g. hypohalogenation
  • C07C45/305—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with halogen containing compounds, e.g. hypohalogenation with halogenochromate reagents, e.g. pyridinium chlorochromate
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D491/00—Heterocyclic compounds containing in the condensed ring system both one or more rings having oxygen atoms as the only ring hetero atoms and one or more rings having nitrogen atoms as the only ring hetero atoms, not provided for by groups C07D451/00 - C07D459/00, C07D463/00, C07D477/00 or C07D489/00
  • C07D491/22—Heterocyclic compounds containing in the condensed ring system both one or more rings having oxygen atoms as the only ring hetero atoms and one or more rings having nitrogen atoms as the only ring hetero atoms, not provided for by groups C07D451/00 - C07D459/00, C07D463/00, C07D477/00 or C07D489/00 in which the condensed system contains four or more hetero rings

Definitions

• the present invention relates to a process for preparation of 2-amino-5-hydroxypropiophenone, a key intermediate for the synthesis of camptothecin analogs including 7-Ethyl-10-hydroxycamptothecin and novel intermediates thereof.
• Camptothecin (herein referred as CPT) a natural alkaloid isolated from the bark of Camptotheca acuminata is known to possess antitumor activity by inhibition of nucleic acid synthesis. Due to some severe side effects of this natural compound, various camptothecin derivatives have been synthesized with reduced toxicity and enhanced antitumor activity.
• One such compound is 7-ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxycamptothecin hydrochloride trihydrate (Generic name: irinotecan; herein referred to as CPT-11).
• Camptothecin analogs such as CPT-11 and others are derived by a chemical synthesis from CPT, which is obtained from plant sources.
• CPT which is obtained from plant sources.
• the amount of CPT obtained from natural plant source is extremely low and the purity of the final CPT-11 is also low ( ⁇ 97%) due to the contamination of related natural products.
• the demand for CPT-11 is increasing and the supply of CPT is gradually reducing.
• camptothecin and camptothecin analogs are known in the art. These synthetic methods include (i) methods in which naturally occurring camptothecin is synthetically modified to produce a number of analogs and (ii) totally synthetic methods.
• Patent Application no. US2004/0106830 A1 discloses the preparation of AB ring (2-amino-5-hydroxycamptothecin) for CPT-11 synthesis starting from either 5-hydroxy-2-nitrobenzaldehyde or from 5-benzyloxy-2-nitrobenzaldehyde as shown in the scheme 2
• the objective of the present invention is to provide a suitable method of producing 2-amino-5-hydroxypropiophenone (herein referred to as compound 11) corresponding to AB ring (part of camptothecin from readily available 3-halobenzaldehyde.
• compound 11 2-amino-5-hydroxypropiophenone
• AB ring part of camptothecin from readily available 3-halobenzaldehyde.
• the reactions are simple to perform and have practical utility.
• the present invention discloses a process for efficient production of 2-amino-5-hydroxypropiophenone corresponding to the AB ring part of camptothecin (CPT) skeleton, which is a key intermediate useful for the total synthesis of camptothecin analogs such as SN-38 and CPT-11.
• CPT camptothecin
• the present invention discloses a process for preparation of 2-amino-5-hydroxypropiophenone (11) which comprises;
• 2-amino-5-hydroxypropiophenone is made starting from 3-halobenzaldehyde by a simple and commercially feasible approach.
• the method can be adopted to synthesize 2-amino-5-hydroxy phenyl alkyl ketones.
• the alkyl group can be 1 to 6 carbons, and if required, can be extended either linear or branched alkyl chain.
• step 1 compound (13) is obtained by reacting a 3-halobenzaldehyde (12) preferably 3-Fluorobenzaldehyde with a Grignard reagent in an inert atmosphere.
• a Grignard reagent is prepared by reacting ethyl halide with magnesium in tetrahydrofuran (referred as THF) or solvent ether.
• THF tetrahydrofuran
• solvent ether solvent ether
• reaction solution is quenched with saturated aqueous ammonium chloride solution and extracted with a solvent. The solvent is removed to give sufficiently pure alcohol (13) to carry forward for the next reaction.
• Compound (13) is oxidized to give 3-halopropiophenone (14).
• the preferred oxidizing agent is Jones reagent (Cr 2 O 3 /H 2 SO 4 ).
• Other reagents can also conveniently be used.
• Oxidation of (13) is carried out in solvent, preferably acetone. During the oxidation, the temperature of the reaction is maintained between 0 to 10° C.
• 5-halo-2-nitropropiophenone (15) can be obtained by nitrating 3-halopropiophenone (14) using a nitrating agent.
• Nitrating agent is selected from nitrating mixture of nitric acid and sulfuric acid or fuming nitric acid. Fuming nitric acid is preferred for nitration.
• the nitration is carried out with or without solvent. During the nitration, the temperature is controlled by external cooling. The preferred temperature to carry out the nitration reaction is ⁇ 5° to 5° C. The nitration is completed within 6 to 10 hrs depending upon the batch size. At the end of nitration, the reaction solution is poured over ice or ice/water mixture and stirred to give solid.
• the nitro compound (15) is extracted with a solvent such as DCM or chloroform and washed with water. The solvent is removed to give the desired nitro compound (15).
• the compound (15) obtained in the above step is pure enough to carry forward
• Compound (15) is then converted to a 5-protected or 5-unprotected propiophenone derivative.
• the protected derivative wherein R is methyl is obtained by treating compound (14) with a suitable alkoxide.
• R is methyl
• the methanolic solution of a hydroxide is used. Methanolic sodium hydroxide is preferred.
• Other hydroxides in alcohol can also be used.
• the above reaction is carried at 0-10° C. for 2 to 5 hrs.
• the alkaline medium is acidified to adjust the pH ⁇ 2-4 with mineral acid and the solvent is removed.
• the extraction is carried out with a solvent, preferably DCM and organic layer, washed with water. The solvent is removed to give 5-methoxy-2-nitropropiophenone, which is sufficiently pure to take to the next step.
• the protected derivative wherein R is ethyl is obtained by treating compound (14) with sodium hydroxide in ethyl alcohol to give 5-ethoxy-2-nitropropiophenone, using similar procedures mentioned above.
• 5-halo-2-nitropropiophenone (15) can directly be converted to 5-hydroxy-2-nitropropiophenone (17) by heating with inorganic base in aqueous medium.
• the 5-alkoxy compound can be smoothly converted to the corresponding phenolic compounds by deprotection on reacting with HBr, HI, Lewis acids, mercaptans, and the like by known procedures and also by heating with metal salts in suitable polar solvent.
• suitable polar solvents are selected from DMF, DSMO, DMA or N-methyl pyrrolidine.
• the preferred method of demethylating 5-methoxy-2-nitropropiophenone to give 5-hydroxy-2-nitropropiophenone (17) is by heating with lithium chloride in DMF at reflux temp for 2 to 10 hrs. Deprotection can also be effected with Lewis acids. Thus, the 5-ethoxy compound is deprotected using ZnCl 2 in conc. HCl.
• Compound (17) is purified by diluting the crude mixture with water and extracting into ethyl acetate and removal of solvent. Isolation of pure 5-hydroxy-2-nitropropiophenone may require use of silica gel column chromatography.
• the compound (17) is then converted to 2-amino-5-hydroxypropiophenone (11) by reduction of the nitro group using reducing agent.
• the compound (17) can be reduced using various reducing agents including hydrogenation in presence of any suitable catalyst such as Raney nickel or Pd/C.
• the preferred method of reducing compound (17) is by sodium dithionite in alkaline medium.
• compound (17) is taken in methanol and added to a suspension of sodium dithionate and sodium carbonate in water and the reaction is best carried out at 0 to 30° C. for 2 to 5 hrs to obtain 2-amino-5-hydroxypropiophenone.
• the 2-amino-5-hydroxypropiophenone thus obtained is purified by crystallization from suitable organic solvent.
• Toluene is the preferred solvent for the crystallization of compound.
• the compound thus obtained is more than 98% pure, by HPLC.
• the 2-amino-5-hydroxypropiophenone (11), thus obtained is condensed with cyclic triketone (4) by Friedlander reaction, known in the art, in toluene in presence of acetic acid and p-toluene sulfonic acid to give SN-38.
• the said reaction is carried out at 100° C. for 15-20 hrs.
• the solvent is removed, reaction mass taken in acetic acid and diluted with ethanol to provide SN-38 as a colourless compound, having purity greater than 99.5%.

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• 2005
  • 2005-09-27 WO PCT/IN2005/000326 patent/WO2007015259A2/fr not_active Ceased
  • 2005-09-27 ES ES05796470T patent/ES2432553T3/es not_active Expired - Lifetime
  • 2005-09-27 EP EP05796470.2A patent/EP1910269B1/fr not_active Expired - Lifetime
  • 2005-09-27 US US11/997,688 patent/US7608740B2/en not_active Expired - Lifetime

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